Diab, who resigned as prime minister in the wake of the port explosion on August 4 but stayed on as caretaker PM, claimed that the evening before it happened he tasked the country's public works minister and justice minister with investigating about 2,750 metric tons of the chemical that arrived in the city on a ship in 2013.

Documents forwarded to the ministries as part of the probe made clear just how dangerous the ammonium nitrate could be and warned that "setting it alight will cause a large explosion and its outcome will be the near total destruction of the port."

CNN has seen some of the documents enclosed in a file sent to the Public Works Ministry.

Public Works Minister Michel Najjar reviewed the documents late on August 3 and instructed officials in the ministry to follow up on the matter, according to the caretaker prime minister's office. A stamp on the documents received by the ministry was dated August 4, 2020 -- the same day Beirut's port was torn apart when the chemical detonated.

CNN has sought comment from Najjar and has not received a response.

At least 204 people were killed, and thousands more injured in the explosion that ripped through the Lebanese capital. The blast, which left an orange mushroom cloud towering over the city, caused extensive damage to Beirut's central and eastern districts, displacing around 300,000 people from their homes.

More than four months on, what triggered the detonation of the material remains unclear, but government officials have said that they have not ruled out sabotage.

"Everything that's happening is suspicious," Diab told CNN. "There's something that's unexplainable, the timing of this, what's happening."

Diab has been charged with criminal neglect as part of a judicial probe into the blast.

He denies the charge and says he has been singled out despite the fact the explosive material had been stored at the port for around six years before he took office.

"You must ask the questions: Who brought the ship? Who owns it? Who paid for it? Who was silent about it for seven years?" Diab said.

Since the ammonium nitrate arrived in Beirut, Lebanon has had four prime ministers, including the country's current Prime Minister-designate Saad Hariri,

who has denounced the charging of Diab.

Three ex-ministers also face charges in connection with the deadly blast.

Diab -- who had already submitted a voluntary affidavit -- declined to be questioned by the judge leading the investigation, saying it lacks a constitutional basis.

The investigation was suspended, after two of the ex-ministers facing charges requested that the judge be removed from the case.

The documents forwarded to the public works ministry before the blast raised the possibility that the explosive material could be stolen; they warn of a broken door at the warehouse where the deadly material was stored, and reveal that security there was scant.

A Lebanese intelligence official told CNN that 1,300 tons of ammonium nitrate had gone missing from the warehouse prior to the explosion.

Diab's government, which will be replaced when a new cabinet is formed, has repeatedly acknowledged receiving prior warnings about the dangers posed by the storage of the explosive material at the port.

Previous governments were also notified about the warehouse, but no one addressed the problem.

'No regrets'

Diab has repeatedly accused Lebanon's ruling elite of "besieging" his government and upending its plans to carry out a series of economic and political reforms.

He took power in January 2020, months after a popular uprising engulfed the country, and as the crisis-ridden country was approaching a financial meltdown.

A technocrat and a professor at the American University of Beirut, Diab has headed a largely technocratic government that was ushered in by a Hezbollah-backed parliamentary majority.

But his tenure has seen the country's currency tank, the coronavirus pandemic take hold, poverty levels soar and Beirut's port destroyed.

Diab says his government "was an opportunity for Lebanon to retrieve some of its losses, economic, social, financial."

"With the support of political parties, with the support of the (Arab) Gulf (countries), with the support of the Europeans and Americans, we would have made a big, huge difference and we were not provoking anyone," he said.

"In a country like Lebanon ... you need consensus, and you need support from the international community as well, and the Gulf. None of these were forthcoming."